well have you learnt all his other Limits? these are them:
Level 1:Sled Fang, Lunatic High,
Level 2:Blood Fang, Stardust Ray,
Level 3:Howling Moon, Earth Rave.
Once you learn these go to the item menu and chose his Limit Break. make sure he is on your team and give it to him. he should take it. if he doesn't ,even if you know all his other Limit Breaks, then something definatly is wrong.